Thrombosis is one of the major problems of modern man and research directed to its control is a major health goal. The proposed program is designed to maintain an interdisciplinary Thrombosis SCOR at Cornell University Medical College. The activity represents the combined interrelated efforts of eight major laboratories all working on the fundamental biochemical and physiological background of the human thrombotic process. The long aim of the program is to clarify and define thrombogenesis in meaningful clinical terms which may have eventual therapeutic relevance in man. An underlying theme which serves as a common denominator of the individual projects is the recognition and definition of the basic cellular and biochemical determinants of the thrombotic process. The coordinated interrelationships of platelets, endothelial cells and circulating protease inhibitors as important denominators of localized events will be stressed. Models to determine the etiology and pathogenesis of atherosclerosis will be studied.